The only 2D design I've ever done, and my proudest achievement. I was fortunate enough to work on this project during a summer job in my student days. As the only mechanical design student in a room full of Civil Engineers, I was asked to develop the mechanism to allow the maintenance crew to change the lightbulbs without having to hang out over the parapet.
I've no idea whether or not they went with my idea but it was an honour to work on this project at such an early age.